How you straighten the edge of a crooked board depends on the severity of the defect. If the crook is mild, run the concave edge over your jointer to straighten it. Use caution to prevent the leading end from catching on the outfeed table.

To put a straight edge on
a crooked board, stick
it on a long, straight
carrier, such as a strip
of plywood (about
3/4 x 8 x 60"), using
double-faced tape.
Guide the carrier along
the tablesaw fence to rip
off one bad edge.

For boards with severe crook, options exist. You can crosscut the board into shorter pieces, then joint each. You also can rip off the crooked edge at the tablesaw using a long carrier board, as shown in Photo A, right. Or snap a straight line on the board, cut it with a handheld circular saw, then joint the edge smooth.

I had a few pieces of Oak that were crooked and my solution, due to limited space and tools, was to align and clamp the board with the outside crook parallel to the edge of my workbench then use a HD trim bit in my router to straighten the crook. Then I ran the routed edge through my joiner and finally used this straight edge to guide the board through my table saw to trim the inside crook off for a nice straight board.

There is nothing wrong with knots. Knots and the grain around them add character and color to the wood. Small knots can be glued in place with super glue, larger ones with gorilla glue before processing the wood.

The other day, I needed to clean up rough edges on 4' boards. Rather than use a carrier strip requiring extra steps to install/remove double-sided tape, I clamped an 8' length of 2"x2" angle aluminum onto my fence over a 1/4" spacer to lift it off the table saw slightly. This gave me an 8' long fence that the rough boards could ride against... a charm. Quick work of all the boards -- even with resetting the fence position for different board widths.